* {
    padding:0px;
    margin: 0px;
}


/* 顶部导航栏部分 */
.top_nav{
    width:100%;
    height: 30px;
    background-color: #333333;}
.top_nav>.nav_center{
    width:1200px;
    height: 30px;
    margin: auto;}
.top_nav>.nav_center>div{
    width:50%;
    height: 30px;
    float:left;}
.top_nav>.nav_center>div>a{
    height: 30px;
    display: block;
    text-decoration: none;
    font-size:14px;
    color:#EEE;
    line-height: 30px;
    box-sizing: border-box;}
.top_nav>.nav_center>.left>a{
    float:left;
    margin-right: 15px;}
.top_nav>.nav_center>.right>a{
    float:right;
    margin-left: 15px;}
.top_nav>.nav_center>div>a:hover{
    font-weight: bold;
    color:#188EEE;
    border-bottom: 3px #188EEE solid;}
.top_nav::after{
    content: "";
    display: block;
    clear: both;}

/* 标题栏部分 */
.header{
    width:1200px;
    height:90px ;
    margin:auto;
}
.header>div{
    width:50%;
    height: 90px;
    float:left;
    box-sizing: border-box;
    position: relative;
}
.header>.logo>img:nth-child(1){
    padding-top:17px;
    margin-right: 20px;
}
.header>.search>form>input[type=text]{
    width:350px;
    position: absolute;
    right: 0px;
    top:35px;
    box-sizing: border;
    border:2px solid #ccc;
    border-radius: 4px;
    font-size:14px;
    background-color: white;
    background-image: url('https://static.runoob.com/images/mix/searchicon.png');
    background-position: 10px 7px;
    background-repeat: no-repeat;
    padding: 8px 20px 8px 40px;
}
.header::after{
    content: "";
    display: block;
    clear: both;}


/* 导航栏 */
.nav{
    width:1200px;
    height: 40px;
    margin: auto;
}
.nav>div{
    float:left;
}
.nav>.left{
    width:200px;
    height: 40px;
    background-color: #188EEE;
    position: relative;
    box-sizing: border-box;
    padding:7px 0 0 60px;
    font-size:18px;
    color:white;
}
.nav>.left>img{
    position: absolute;
    left: 30px;
    top: 10px;
}
.nav>.right{
    height: 40px;
    padding-left: 20px;
}
.nav>.right>a{
    text-decoration: none;
    display: inline;
    margin:18px;
    font-size:13px;
    line-height: 40px;
    color:#111;
}
.nav>.right>a:hover{
    color:#188EEE;
    font-weight: 700;
}
.nav::after{
    content: "";
    display: block;
    clear: both;}


/* 大图部分 --- 导航栏 */
.big_img{
    width:100%;
    height: 340px;
    background-color:#C3C864}
.big_img>.img_center{
    width:1200px;
    height: 340px;
    margin: auto;
    position: relative;}
.big_img>.img_center>.course_type{
    width:200px;
    height: 340px;
    position: absolute;
    top:0px;
    left:0px;
    background-color:rgba(0,0,0,.7);}
.big_img>.img_center>.course_type>.item{
    width:200px;
    height: 68px;
    padding: 5px;
    box-sizing: border-box;}
.big_img a{
    color:white;
    text-decoration: none;}
.big_img h5 a{
    display: inline;
    margin-right: 5px;
    font-size:14px;
    line-height: 35px;}
.big_img p a{
    display: inline;
    font-size:13px;
    margin-right: 5px;
    line-height: 15px;}
.big_img>.img_center>.course_type>.item:hover{
    background-color:navy;}
.big_img a:hover{
    color:#188EEE;}

/* 大图部分 --- 新闻栏 */
.big_img>.img_center>.news{
    width:240px;
    height: 280px;
    background-color:#161B29;
    position: absolute;
    right: 0px;
    top:30px;
    box-sizing: border-box;
    border-radius: 10px;
    padding: 15px;}
.big_img>.img_center>.news h3{
    color:#188EEE;}
.big_img>.img_center>.news hr{
    margin: 10px 0px;}
.big_img>.img_center>.news li{
    color: #EEE;
    list-style-position: inside;}
.big_img>.img_center>.news a{
    text-decoration: none;
    color:#EEE;
    font-size:14px;
    line-height: 22px;}
.big_img>.img_center>.news li:hover{
    color:#188EEE;}
.big_img>.img_center>.news a:hover{
    color:#188EEE;}


/* 内容标题头部 */
.content_header{
    width:1200px;
    height: 60px;
    margin: auto;

}
.content_header>div{
    width: 1200px;
    height: 46px;
    margin-bottom: 5px;
}
.content_header>div>div{
    float:left;
    width:50%;
    height: 46px;
}
.content_header>div>.left>*{
    float:left;
}
.content_header>div>.left>h2{
    line-height: 46px;
    letter-spacing: 5px;
}
.content_header>div>.left>img{
    margin-right: 30px;
}
.content_header>div>.right>a{
    display: block;
    float:right;
    line-height: 46px;
    margin-left: 25px;
    text-decoration: none;
    font-size:14px;
    color:#111;
    font-weight: bold;
}
.content_header>div>.right>a:hover{
    color:#188EEE;
}

/* 内容区域--畅销好课 */
.content{
    width: 1200px;
    height: 230px;
    margin: 10px auto;
}
.content>.course{
    width:285px;
    height:230px;
    float:left;
    margin-right: 20px;
}
.content>.course:last-child{
    margin-right: 0px;
}
.content>.course>img{
    width:285px;
    height: 150px;
    display: block;
}
.content>.course>div{
    width:285px;
    height: 80px;
    background-color: #F5F5F5;
    padding: 5px 10px;
    box-sizing: border-box;
}
.content>.course>div>h5{
    font-size:15px;
    line-height: 25px
}
.content>.course li{
    list-style-type: none;
    font-size:14px;
    line-height: 20px;
    margin-right: 15px;
}
.content>.course>div>.middle>li{
    display: inline;
   
}
.content>.course>div>.middle>li:first-child::before{
    content: "作者：";

}
.content>.course>div>.middle>li:last-child::after{
    content: "人好评";
}
.content>.course>div>.price>li{
    display: inline;
}
.content>.course>div>.price>li:first-child{
    text-decoration: line-through;
}
.content>.course>div>.price>li:first-child::before{
    content:"原价：￥";
}
.content>.course>div>.price>li:last-child{
    color:red;
}
.content>.course>div>.price>li:last-child::before{
    content:"优惠价：￥";
}
.content>.course>div>h5:hover{
    color:#188EEE;
}
.content>.course:hover{
    box-shadow: 0px 0px 1px 2px navy;
}


/* 内容部分--学生必读 */
.content_reader{
    width:1200px;
    height: 340px;
    margin: auto;
}
.content_reader>.item{
    width:390px;
    height: 340px;
    background-color:lightblue;
    margin-right: 15px;
    float:left;
    box-sizing: border-box;
    padding:20px;
}
.content_reader>.item:last-child{
    margin-right: 0px;
}

.content_reader>.item li{
    list-style-position: inside;

}
.content_reader>.item h2{
    line-height: 40px;
}
.content_reader hr{
    margin: 10px 0px;
}
.content_reader>.item a{
    text-decoration: none;
    color:navy;
    line-height: 35px;
}
.content_reader>.item a:hover{
    color:red;
    font-weight: bold;
}

/* 页脚部分 */
.footer{
    width:100%;
    height: 230px;
    background-color: #333;
}
.footer>div{
    width:1200px;
    height: 230px;
    margin:auto;
}
.footer>div>div{
    width:200px;
    height: 230px;
    float:left;
    box-sizing: border-box;
    padding: 20px;
}
.footer>div>div h3{
    line-height: 50px;
    color:white;
}
.footer>div>div a{
    display: block;
    text-decoration: none;
    color:#EEE;
    line-height: 25px;
}
.footer>div>div:nth-child(5){
    color:white;
    box-sizing: border-box;
    padding-top: 80px;
}
.footer>div>div:nth-child(6){
    box-sizing: border-box;
    padding: 30px;
}


.footer>div>div a:hover{
    color:#188EEE;
}